This invention relates to 3-ply trash bags containing skin layers of high performance polyolefin films prepared by a sandwich foam coextrusion process.
Since about 1978, high performance polyolefins, such as linear low density polyethylene polymers, have been available at sufficient cost and quantity to justify their commercial use in trash bags including heavy duty garbage bags, leaf bags and trash can liners. By use of such polymers, bags of remarkably thin gauge and flexibility can be achieved without sacrificing the strength characteristics of thicker gauge bags made from other polymers. However, high performance polyolefin bags of thin overall gauge tend to have a "limp", "flimsy" feel. Accordingly, even though such thin bags may have more than adequate stength for trash containment, the user may refrain from using these bags, because he may be misled by the flimsy feel of the bags. If a bag breaks because of misuse, the user may tend to unjustifiably blame the breakage on the thin nature of the bag.
In addition to having a high degree of strength per unit thickness, bags composed primarily from high performance polyolefins tend to have a high degree of flexibility. These properties present a number of handling problems to the user of the bag. First of all, for example, when the opposing walls of the bag are folded one on the other in the conventional orientation for packaging a number of bags, these walls lack sufficient independent structural integrity to stand alone and tend to conform tightly one to another. Accordingly, it is often difficult to locate the opening of the bag, and, once the opening is located, the opposite walls of the bag often must be peeled apart. Another problem associated with the large degree of flexibility of the walls is that the walls will tend to collapse, e.g., when the bag is held in the open position. More particularly, when one attempts to hold such a flexible bag open by grasping and spreading opposite ends of the opening in an attempt to form a more or less circular configuration, the ungrasped portions of the bag tend to droop in a frustrating fashion. It can be extremely difficult to load trash or leaves in a bag with such a droopy opening.
Even when a circular opening is maintained by using such a light weight flexible trash bag as a trash can liner, problems may still result from excessive flexibility. For example, the bag may tend to fold in on itself instead of conforming to the shape of the trash receptacle. This folding may result in the bag being subjected to excessive destructive forces, e.g., when heavy objects are thrown into the receptacle.
Accordingly, there is a need to impart improved structural properties to trash bag structures having high performance polyolefins.